Number of reference fields for an interlaced forward-predicted field

Abstract

Techniques and tools for signaling the number of reference fields for an interlaced forward-predicted field are described. For example, a video decoder processes a first signal indicating whether an interlaced forward-predicted field has one or two reference fields for motion compensation. If the first signal indicates the interlaced forward-predicted field has one reference field, the decoder processes a second signal identifying the one reference field from among the two reference fields. On the other hand, if the first signal indicates the interlaced forward-predicted field has two reference fields, for each of multiple motion vectors of the interlaced forward-predicted field, the decoder processes a third signal for selecting between the two reference fields. A video encoder performs corresponding signaling.

Description

COPYRIGHT AUTHORIZATION A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. TECHNICAL FIELD Techniques and tools for interlaced video coding and decoding are described. For example, a video encoder and decoder use signaling of the number of reference fields available for an interlaced P-field. BACKGROUND Digital video consumes large amounts of storage and transmission capacity. A typical raw digital video sequence includes 15 or 30 frames per second. Each frame can include tens or hundreds of thousands of pixels (also called pels), where each pixel represents a tiny element of the picture. In raw form, a computer commonly represents a pixel as a set of three samples totaling 24 bits. For insta...

AI Technical Summary

Problems solved by technology

Digital video consumes large amounts of storage and transmission capacity.

Many computers and computer networks lack the resources to process raw digital video.

Compression can be lossless, in which the quality of the video does not suffer, but decreases in bit rate are limited by the inherent amount of variability (sometimes called entropy) of the video data.

Or, compression can be lossy, in which the quality of the video suffers, but achievable decreases in bit rate are more dramatic.

In certain encoding/decoding scenarios (e.g., high bit rate interlaced video with lots of motion), limiting motion compensation for forward prediction to be relative to a single reference can hurt overall compression efficiency.

Problems with Previous Signaling of Macroblock Information

While this signaling provides good overall performance in many cases, it does not adequately exploit statistical dependencies between different signaled information in various common cases.

Further, it does not allow and address various useftl configurations such as presence/absence of CBPCY for 4MV macroblocks, or presence/absence of motion vector data for 1MV macroblocks.

And, the signaling does not allow and address various useful configurations such as presence of coefficient information when motion vector data is absent.

In certain encoding/decoding scenarios (e.g., high bit rate interlaced video with lots of motion), limiting motion compensation for forward prediction to be relative to a single reference can hurt overall compression efficiency.

The reference field selection signals for the motio

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